A hydrocarbon resource may be particularly valuable as a fuel, for example, gasoline. One particular hydrocarbon resource, bitumen, may be used as a basis for making synthetic crude oil (upgrading), which may then be refined into gasoline. Accordingly, bitumen, for example, may be relatively valuable. More particularly, to produce 350,000 barrels a day of bitumen based synthetic crude oil would equate to about 1 billion dollars a year in bitumen. Moreover, about 8% of U.S. transportation fuels, e.g., gasoline, diesel fuel, and jet fuel, are synthesized or based upon synthetic crude oil.
In the hydrocarbon upgrading or cracking process, hydrogen is added to carbon to make gasoline, so, in the case of bitumen, natural gas is added to the bitumen. Natural gas provides the hydrogen. Bitumen provides the carbon. Certain ratios and mixes of carbon and hydrogen are gasoline, about 8 carbons to 18 hydrogens, e.g. CH3(CH2)6CH3. Gasoline is worth more then either bitumen or natural gas, and thus the reason for its synthesis. Thus, produced bitumen may be a relatively important source of carbon.
The United States and Canada have vast bitumen and heavy oil resources. Unfortunately however, the oil may often be too thick or the reservoir may be too impermeable to permit economic recovery. This may strand hydrocarbons within the subterranean formation, and thus stranded and enhanced oil recovery (EOR) techniques may be desired, such as horizontal directional drilling or steam injection, for example.
Radio frequency (RF) heating may provide enhanced oil recovery. In RF heating, a RF heating applicator may be placed in the subterranean formation, and electromagnetic energy may be applied to warm and thin the hydrocarbon resources. RF heating may increase the speed of the recovery and may increase the present value. RF heating may even be used to initiate the convection of injected steam due to the rapid penetration of RF electromagnetic fields, for example. A 1 kilometer long subterranean RF radiator may include electrical conductors 2000 to 3000 meters long that convey 5 megawatts of power.
Several references disclose application of RF to a hydrocarbon resource to heat the hydrocarbon resource, for example, for cracking. In particular, U.S. Patent Application Publication No. 2010/0219107 to Parsche, which is assigned to the assignee of the present application, discloses a method of heating a petroleum ore by applying RF energy to a mixture of petroleum ore and susceptor particles. U.S. Patent Application Publication Nos. 2010/0218940, 2010/0219108, 2010/0219184, 2010/0223011, 2010/0219182, all to Parsche, and all of which are assigned to the assignee of the present application disclose related apparatuses for heating a hydrocarbon resource by RF energy. U.S. Patent Application Publication No. 2010/0219105 to White et al. discloses a device for RF heating to reduce use of supplemental water added in the recovery of unconventional oil, for example, bitumen.
Several references disclose applying RF energy at a particular frequency to crack the hydrocarbon resource. U.S. Pat. No. 7,288,690 to Bellet et al. discloses induction heating at frequencies in the range of 3-30 MHz. More particularly, radio frequency magnetic fields are applied to ferrous piping that includes hydrocarbons. The magnetic fields induction heat the ferrous piping and the hydrocarbons inside are warmed conductively. Application Publication No. 2009/0283257 to Becker discloses treating an oil well at a frequency range of 1-900 MHz and no more than 1000 Watts, using a dipole antenna, for example.
U.S. Pat. No. 7,115,847 to Kinzer discloses a method of capacitive RF heating using impedance matching techniques to increase efficiency of hydrocarbon resource recover. More particularly, Kinzer discloses setting a signal generating unit to an initial frequency and changing the frequency based upon a load impedance.
Further improvements to hydrocarbon resource recovery, or heating or upgrading may be desirable. For example, it may be desirable to increase the efficiency of startup of an un-insulated well by making it quicker and cheaper, for example.